1. Field of the Invention
The invention relates to the field of aircraft communications equipment and in particular to communication systems used to provide communications between the ground crew, cabin crew and flight crew. The invention relates to two or multi-way radio systems and communication networks for use with aircraft operation and service, either within or from outside the cabin.
2. Description of the Prior Art
Under current aircraft ground communication systems, a ground crew person communicates with the cockpit using either a headset or handset. The headset or handset has an integral earphone, microphone, and Push-to-Talk (PTT) elements. These elements are connected through wires to a plug, and the plug is inserted into an audio jack on the exterior of the aircraft, usually concealed within a covered access hatch or to a jack within the cabin of the aircraft. There are two such communication systems on typical commercial and military aircraft providing such communications, and in the industry these systems are referred to as aircraft interphone systems.
During arrival, dispatchment, flight, and maintenance, a communications system is necessary for those members operating or conducting activities in or about an aircraft. To accommodate these activities a communications system is incorporated into the aircraft. Referred to as the aircraft interphones, there are typically three independent interphone systems: cabin interphone, service interphone and to a lesser extent, flight interphone.
All interphone systems on aircraft are designed and operate in similar fashion. Specifically, there are a series of two-way audio connections where audio is brought into a central amplifier and distributed back out on a “party line” network. In this type of communication architecture a crewmember couples onto the network using a corded headset or handset. Once connected, any crewmember's handset, or headset hears any audio intelligence across the network. Should the crewmember desire to communicate as well, then he or she merely engages their microphone by pressing their Push-to-Talk (PTT) switch.
There are some phases of flight that are deemed very important to aircraft operation. Two such phases are departure and landing, and the following provides further details about these phases.
Departure
During the departure phase a ground crew person responsible to pushing the aircraft away from the terminal will plug their headset into the interphone system on the side of the aircraft in order to communicate with the cockpit. Once the aircraft is pushed back from the gate and terminal area and when the push bar is disconnected and clear of the aircraft, the ground crew person will inform the flight crew the aircraft is ready for flight.
Under current means a long cable, cable extensions, or cable reel systems (See U.S. Pat. Nos. 5,453,585 and 6,241,063), are necessary to connect the ground crew person to the audio interphone jack on the aircraft. Since the ground crew operates the tractor at a distance from the aircraft body, the cable, and/or any extensions, are susceptible to entanglement and damage about the push bar and tractor machinery. Should communications between the ground crew person and the cockpit fail at this time, departure would be delayed.
Landing
In consideration of commercial passenger aircraft, there are two cases of landing to be concerned with; normal and emergency landings. During landing of commercial aircraft flight attendants must inform passengers to “ready the aircraft for landing” (i.e. stow baggage, place tray tables upright, and secure infants), and theses announcements are stated through a corded handset from a fixed location within the aircraft. Additionally, the flight attendants must verify cabin readiness for landing, so they move about inspecting the cabin after the announcement is made. During an emergency situation though, the period of time to ready the cabin is abbreviated.
Currently, a flight attendant will inform passengers regarding landing procedures from a short length corded handset in a fixed location. This approach requires an announcement to be made first, and inspection of cabin's readiness for landing secondary. Should a long cable be employed in order to allow the flight attendant to announce landing procedures and check the cabin concurrently, the cable can easily become entangled or damaged. Alternatively, should the announcement station realize a failure, the announcement is delayed.
Prior art systems typically employ a headset consisting of earphones, two pieces that surround both left and right ears of the head, a microphone that is mounted to one earphone and extended in front of the user's mouth, a Push-to-Talk (PTT) switch that is integrated with the connecting cord, and a plug that serves as a coupling means with the aircraft interphone system. This does not preclude, however, the earphones, microphones and PTT switch being separated or packaged differently.
In an alternate form called a handset, a singular earphone is integrated with the microphone and PTT switch, and all are contained most typically within a plastic structure that very closely resembles a telephone handset. The unique cosmetic difference between a discrete, corded telephone handset and an aircraft handset is the PTT switch and the cable plug.
In both prior art arrangements the coupling plug is inserted into a jack of the aircraft interphone system. This system has certain amplifiers, microphone bias, and distributed wired jacks throughout the aircraft. Within the aircraft, interphone jacks can be found in the cockpit for the flight crew (e.g. Pilot and First Officer), and in the cabin at strategic points. For commercial passenger aircraft, for example, these strategic locations can be the Forward cabin (i.e. First Class), Mid-cabin (i.e. Business Class), and Aft cabin (i.e. Coach Class). For military aircraft these locations will differ, though the intention is the same. And on the outside of the aircraft, interphone jack locations can be found at the nose, landing gear wells, wing tips, and cargo areas.
In regular operation the cockpit (i.e. Pilot or First Officer) may converse with a ground crewperson on the ground. Assuming both parties are plugged in the interphone system, they will merely activate the PTT switch that gates, or enables, their respective microphone and then carry out spoken communications.
In summary, there are some basic problems with these interphones systems, namely:                The crew is restricted by the wired nature of such systems to a short distance of movement about the aircraft.        Communication between the cockpit and crew is interrupted when the cable is inadvertently pulled from the audio jack or the cable is pinched or torn.        The cabling between the aircraft and crew is susceptible to damage when maximum cord length is exceeded.        Longer cables, cable extensions, and cable reel systems increase the probability of entanglement.        
What is needed is some type of communication system which is practical, robust, can be used in the typical environment of aircraft operation and which is economically manufactured.